Traction fluids rely on its high shear strength to provide torque transmission in devices like continuous variable transmission (CVT) or infinite variable transmission (IVT). Such transmission allows seamless integration with internal combustion engine for optimal engine performance and maximum fuel efficiency. In the year 1999, toroidal continuous variable transmission (T-CVT) cars were introduced in the market and the traction fluid used for the T-CVT required high level of performance in terms of high traction coefficient and low temperature fluidity of the molecule.
The shear strength can be measured as traction coefficient and it is the higher the better. Cycloaliphatic hydrocarbons usually possess superior shear strength property, but have poor low temperature viscosity properties. To balance these properties, fluids with good low temperature viscosity properties such as silicone, ester, or poly alpha olefin (PAO) can be incorporated into the practical traction fluids.